ABSTRACT
BACKGROUND: The objective of the present phase I study was to define the dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD) of irinotecan, capecitabine, and oxaliplatin given in combination (IXO regimen) to patients with previously untreated, unresectable advanced or metastatic colorectal cancer (CRC). PATIENTS AND METHODS: Patients received oxaliplatin followed by irinotecan as intravenous infusions on day 1, with oral capecitabine taken twice daily (BID) on days 2 to 15 of a 3-week cycle. The dose ranges were explored as follows: oxaliplatin, 75 to 120 mg/m2; irinotecan, 160 to 230 mg/m2; capecitabine, 750 to 1000 mg/m2 BID. Dose escalation was performed individually for each drug at each dose level according to the type and severity of toxicity encountered in the previous cohort. RESULTS: A total of 39 patients were enrolled at 7 dose levels and the MTD. The recommended doses for phase II evaluation were oxaliplatin 100 mg/m2, irinotecan 160 mg/m2, and capecitabine 950 mg/m2 BID. Diarrhea and febrile neutropenia were DLTs. Of the 39 enrolled patients, 26 (67%) had confirmed objective responses. The median progression-free survival was 11 months, and the median overall survival was 25 months. The survival rate at 5 years was 23%. CONCLUSION: The IXO regimen has a manageable toxicity profile with promising antitumor activity as first-line treatment of advanced and metastatic CRC.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/adverse effects , Capecitabine , Colorectal Neoplasms/drug therapy , Irinotecan , Oxaliplatin , Adult , Aged , Capecitabine/administration & dosage , Capecitabine/adverse effects , Colorectal Neoplasms/mortality , Disease-Free Survival , Female , Humans , Irinotecan/administration & dosage , Irinotecan/adverse effects , Kaplan-Meier Estimate , Male , Maximum Tolerated Dose , Middle Aged , Oxaliplatin/administration & dosage , Oxaliplatin/adverse effectsSubject(s)
Antineoplastic Agents/adverse effects , Drug Eruptions/etiology , ErbB Receptors/antagonists & inhibitors , Neoplasms/drug therapy , Clinical Trials as Topic , Disease Progression , Disease-Free Survival , Drug Eruptions/classification , Drug Eruptions/therapy , Enzyme Inhibitors/adverse effects , Humans , Phosphotransferases/antagonists & inhibitors , Telangiectasis/chemically induced , Terminology as Topic , Treatment OutcomeABSTRACT
BACKGROUND: We hypothesized excess resistance factor ("active resistance") gives a dose--response curve (DRC) shoulder, deficiency of a factor required for drug sensitivity ("saturable passive resistance") gives a DRC terminal plateau, and alteration of a factor gives decreased DRC slope. METHOD: We used response rates from published non-small cell lung cancer (NSCLC) clinical studies to estimate mean percent tumor cell kill in each study (assuming cell kill is proportional to tumor volume change) and performed regression and meta-regression analyses of percent cell survival and patient survival vs planned dose-intensity. RESULTS: As single agents, cell kill approached that of combinations only at highest doses. While DRC shape varied between single agents, DRCs for all combinations tested flattened at higher doses. Patient median survival times also failed to vary significantly with dose for any combination. CONCLUSIONS: DRC flattening at higher doses suggests therapy efficacy is limited by deficiency/saturation of factors required for cell killing. Based on this and other clinical observations, we hypothesize: (1) active resistance may modulate cell killing at lower doses, but ability to overcome this by increasing doses is limited by saturable passive resistance (e.g. by non-cycling cells). (2) Cells surviving initial chemotherapy may upregulate active resistance mechanisms (permitting growth despite therapy). (3) If active resistance mechanisms are insufficient for growth/survival, cells may survive until therapy cessation by downregulating metabolism/cycling, becoming temporarily quiescent. This could help explain broad cross-resistance between agents and would imply that improved targeting of non-cycling cells will be required for major improvement in therapy efficacy.
